Cool cutting polycrystalline diamond cutting element

Abstract

A PDC cutting element is described with a high abrasion thermally stable cutting edge that is supported by a diamond matrix which presents a non-planar wear surface to the rock interface. The non-planar wear surface of the supporting layer dramatically reduces the amount of heat generated at the PDC rock interface and provides rapid cutting with less weight on the bit for deep hole drilling applications.

1 . A polycrystalline diamond construction comprising:
 a first surface of a uniform first matrix of sintered together diamond grains;   a second supporting matrix of diamond adjacent to the first surface containing a dispersion of agglomerated fine diamond crystals randomly distributed throughout its body wherein the average diameter of the agglomerations is significantly larger than the single crystal diamond used in the matrix; and   a third surface consisting of a supporting substrate attached to the polycrystalline diamond layer.   
     
     
         2 . The construction of  claim 1  wherein the agglomerated fine diamond crystals are pre-sintered with a catalyst sintering aid at high-pressure and high-temperature. 
     
     
         3 . The construction of  claim 2  wherein the pre-sintered agglomerations are leached or otherwise treated to render the catalyst sintering aid inactive. 
     
     
         4 . The construction of  claim 1  wherein the agglomerations are bonded with a non-catalytic sintering aid. 
     
     
         5 . The construction of  claim 1  wherein the second matrix is made up of diamond crystals whose average diameter is at least 2.5 times larger than the diameter of the diamond component particles of the aggregations. 
     
     
         6 . The construction of  claim 1  wherein the average diameter of the aggregations in the second matrix is at least 2.5 times larger than average size of the individual diamond particles of the first matrix. 
     
     
         7 . The construction of  claim 1  wherein the average diameter of the aggregations is larger than 100 microns. 
     
     
         8 . The construction of  claim 1  wherein the volume of the aggregations is between 10 percent and 90 percent of the total volume of the second matrix of diamond particles. 
     
     
         9 . The construction of  claim 1  whereby the first surface has a thickness which is less than the thickness of the second diamond matrix. 
     
     
         10 . The construction of  claim 1  wherein the first surface has a thickness less than about 0.5 mm. 
     
     
         11 . The construction of  claim 1  wherein the second diamond matrix has a thickness greater than about 0.5 mm. 
     
     
         12 . The construction of  claim 1  wherein the substrate is composed of two phases, one of which contains agglomerated fine particles distributed throughout a bulk matrix of similar material of larger particle size. 
     
     
         13 . The construction of  claim 1  wherein the substrate is composed of cobalt cemented tungsten carbide and the tungsten carbide is a matrix of a uniform mix of grains with agglomerated finer particles of tungsten carbide distributed throughout the matrix. 
     
     
         14 . The construction of  claim 1  wherein the first surface is made thermally stable by leaching out substantially all of the catalyst material used to fabricate the diamond construction or otherwise render the catalyst material inactive. 
     
     
         15 . The construction of  claim 1  wherein the aggregations comprise diamond particles with an average diameter less than 1 micron and the matrix diamond has an average particle size greater than 10 microns. 
     
     
         16 . The construction of  claim 15  wherein the agglomerated diamond layer is partially leached of catalytic material or the catalyst is otherwise rendered inactive. 
     
     
         17 . The construction of  claim 1  wherein the first surface is formed of diamond particles having an average grain size of about 15 microns;
 the second surface is formed of agglomerated grains between about 250 microns and about 600 microns in size mixed with 25 micron sized diamond powder; and 
 a cobalt cemented tungsten carbine substrate joined to the first and second layers by sintering at high pressure and high temperature. 
 
     
     
         18 . A method for making a polycrystalline diamond construction including the steps of:
 loading a uniform mix of diamond grains into a suitable container;   loading a mixture of agglomerated fine diamond grains and non-agglomerated diamond grains with substantially larger grain size than that contained in the agglomerations on top of the first layer;   placing a substrate into the container; and   subjecting the mixture and substrate to high-pressure and high-temperature conditions.   
     
     
         19 . A method for making the polycrystalline diamond construction of  claim 18  by making the first surface in a separate high-pressure/high-temperature manufacturing step. 
     
     
         20 . A method for making the polycrystalline diamond construction of  claim 18  by making the first surface in a separate high-pressure/high-temperature manufacturing step and leaching the first surface to remove the catalyst material or otherwise making the catalyst inactive.